1. Field of the Invention
The invention relates to a computer-aided determination of a measure of similarity between a first structure and at least one predetermined second structure.
2. Description of the Related Art
Such a method is disclosed in M. Bierling, Displacement Estimation by Hierarchical Blockmatching, SPIE, Vol. 1001, Visual Communications and Image Processing '88, pp. 942-951, 1988 (Bierling). In this image processing method, in the context of a motion estimation between two chronologically successive images for an image block to be coded, in the chronologically preceding image, an image area is sought which is as similar as possible to the image block to be coded. This is done by determining a sum of the square differences of the pixel-assigned coding information (brightness value or color value) of the pixels of the image block to be coded and of the pixels in an investigated area in the chronologically preceding image. This means that for the comparison of two structures in this approach from Bierling, the entire first structure (an image block to be coded) is compared with a second structure (an area in the chronologically preceding image) in its entirety.
This procedure is extremely costly with regard to the memory space required for storing the structures, and also with regard to the computing time required for determining the measure of similarity (in this case, the measure of similarity is the sum of the square differences).
The following procedure is disclosed in O. Karch and H. Noltemeier, Autonome Mobile Systeme (Autonomous Mobile Systems) 1996, G. Schmidt and F. Freyberger, (Eds.), Zum Lokalisationsproblem für Roboter [Regarding the Localization Problem for Robots], Springer Verlag, ISBN 3-54061-751-5, pp. 128-137, 1996 (Karch & Noltemeier): for the comparison of a structure, the elements of the structure are interpreted as polygonal progressions and the polygonal progressions are compared in their entirety, including the consideration of angles between interconnected elements of the polygonal progressions.
This approach is disadvantageous, particularly in that it is not robust relative to recordings made by a robot for its orientation in a predetermined space. The space is in this case represented by a predetermined, stored map.
If some elements of the polygonal progression are not recorded by the robot, then the method disclosed in Karch & Noltemeier is not robust enough to lead to results of sufficient quality. Moreover, the procedure for the comparison of the recorded image with the map in order to compare structures with one another is extremely computationally intensive.